cant speak for the 6.0l but i can speak for the zf6...mine held fine with the dp tuner 120r setting. Put my injectors in and it still took a fairly healthy tune to slip it but when it slipped, it slipped good!
I asked this question for a buddy and was told by two different guys that their stock clutch didn't make it more than a few miles on extreme street, but the buddy I asked for has been running this tune for probably 2 years now on the stock clutch. I still wouldn't bet on the stock clutch lasting long, I think this kid just babies his truck.